ASW 15 / Astir CS mid-air on crossing climb tracks — FLARM not heeded

In a mid-air collision near Lueneburg, the pilot of an Astir CS was seriously injured; the ASW 15 landed damaged and the Astir crashed unmanned in a residential area. Both gliders had departed Lueneburg cross-country and climbed for 18 s on nearly straight crossing tracks (81 deg). The ASW 15 received a FLARM warning of traffic behind and turned right; the Astir CS continued slightly right-banked. Neither pilot saw the other on the constant-bearing approach and the FLARM warnings were not acted on. After the collision the Astir entered a near-vertical, partly inverted descent and the pilot bailed out.

1. Thermaling cross-country: After separate launches from Lüneburg, the ASW 15 pilot climbed to about 1,100 m and proceeded on his planned 450 km cross-country flight while thermaling under cumulus clouds.
2. Shared thermal area: Both gliders were operating in nearby thermals on similar routes without team-flying coordination or mutual radio contact in Class E airspace.
3. Converging flight paths: In the last 18 seconds before impact, the ASW 15 and Astir CS flew nearly straight on crossing tracks with an 81° angle and small height gain, bringing them into conflict.
4. FLARM alert and turn: A FLARM alert showed another aircraft 380-500 m behind; the ASW 15 pilot turned right under the next cloud at 1,097 m AGL as the Astir CS kept turning right to center the next thermal.
5. Mid-air collision: As the ASW 15 turned and the Astir CS flew in a slight right bank, the two gliders collided at about 1,097 m AGL some 2,100 m northwest of Lüneburg, causing major structural damage to both.
6. Emergency descent actions: The ASW 15 dived but the pilot recovered, while the Astir CS entered a near-vertical, inverted descent and its pilot bailed out and opened his parachute.
7. Crash - serious injury: The ASW 15 landed at Lüneburg unhurt; the unmanned Astir CS was destroyed crashing into a residential area, and its pilot's torn, rotating parachute caused a back injury in a wheat field.